In order to achieve a shift to ultra LSI and to attain higher performance, an atmosphere having greater and greater cleanliness is required for the formation and processing of the elements, and technology for the production of ultrahigh vacuums, ultraclean low pressure atmospheres, ultrahigh purity gas atmospheres, and supply systems has become more important.
Such atmospheres are contaminated by leaks from the outside of the apparatus or the gas piping system, or by desorption of impurities adsorbed to the inner surface thereof. Among these impurities, water molecules adsorbed by the inner surface of the apparatus or the gas piping system, in particular, desorb during manufacturing processes such as, for example, thin film formation or processing, and the contamination of the atmosphere as a result of the desorption of these adsorbed molecules creates a problem in, that it tends to cause a worsening of the characteristics of the elements or of the precision of the processing.
Accordingly, it is necessary to construct such semiconductor manufacturing apparatuses using material having a small adsorbed water content, and from which the adsorbed water desorbs easily and within a short period of time; for this reason, surface treatment, such as planarization treatment, post-oxidation passivation treatment, fluoridation passivation treatment, and the like, is carried out on the surface of the structural material.
In order to produce a highly clean atmosphere containing no moisture, it is necessary to develop materials having little adsorbed water and to develop materials from which adsorbed water desorbs quickly, and methods of evaluation by which the amount of water adsorbed by a wafer or the like can be accurately measured after various types of manufacturing processes.
Conventionally, in the case in which amounts of water adsorbed by piping or the like were measured, methods were employed in which a gas of high purity (for example, Ar gas having a water content of less than 50 ppt) was caused to flow through piping as a carrier gas while subjecting the piping to baking, and the desorbing water content was analyzed by means of an atmospheric pressure ionization mass spectrometer (APIMS) or by the Karl Fisher method.
However, in the method in which an APIMS was employed, a number of hours were required for the water molecules adsorbed by the surface of the sample to completely desorb and for the water content concentration in the carrier gas to return to its original value, so that high speed measurement was not possible, and furthermore, there was an upper limit to the measurement of high moisture concentrations. Furthermore, in the Karl Fisher method, it was unclear whether the water molecules contained in the carrier gas were completely absorbed into the solvent, and furthermore, there was a lower limit to the measurement of low moisture concentrations, so that a method having a high degree of reliability was not available. In this situation, there was a strong demand for a method for measuring adsorbed water content which had high reliability and which was capable of rapid measurement.
The above discussion centered on the field of semiconductor manufacturing technology; however, this is not limited to the semiconductor field, but rather, in the manufacture of magnetic discs, laser discs, and micro devices such as liquid crystals and EL flat plate displays, and the like, as well, in order to attain high performance manufacturing processes, a method for the measurement of water content adsorbed by solid surfaces is very important, as remaining adsorbed water content presents the greatest obstacle.
The present invention has as an object thereof to provide a measurement method and a measuring device for measuring water content, which is capable of measuring water content adsorbed by various samples, with high precision and in a short period of time.